function [Nshape,dNdzeta]=GetTriNshape(NdNum,zeta)
Nshape=zeros(NdNum,1);
dNdzeta=zeros(2,NdNum);

Nshape(1)=1-zeta(1)-zeta(2);
Nshape(2)=zeta(1);
Nshape(3)=zeta(2);

dNdzeta=[-1 1 0;
         -1 0 1];
